The discovery of bird flu in the San Mateo backyard flock prompted health officials to remind people to take biosecurity measures.

The new H5N1 version, known as D1.1, was found in dairy cattle in Nevada and is different than the B3.13 type that has spread to more than 950 herds in 16 states over the past year, starting in Texas. The D1.1 infection was discovered by testing raw milk under a USDA dairy surveillance project launched last year.

State officials say the highly pathogenic avian influenza – more commonly known as bird flu – is widespread in much of the state.